Inter-tube gas burner for a coal or oil-fired waterwall boiler



Feb. 23, 1965 H. N. JAcKsoN 3,170,443

INTER-TUBE GAS BURNER FOR A COAL OR OEL-FIRED WATERWALL BOILER Filed April 29, 1963 4 Sheets-Sheet 1 HERBERT A/E/LL JA c/so/v T TORNEY Feb. 23, 1965 INTER-TUBE Filed April 29,' 196s H. N. JACKSON GAS BURNER FOR A COAL. OR OIL-FIRED WATERWALL BOILER 4 Sheets-Sheet 2 INVENTOR.

HERBERT /VE/LL d CKSO/V ATTORNEY Feb. 23, 1965 H N JACKSON 3,170,443

INTER-TUBE GAS BRNR FOR A COAL OR OIL-FIRED WATERWALL BOILER Filed April 29, 1963 4 Sheets-Sheet 5 ,k Y Alf/A W1 l//A VA V// Iii/A :x Wl

A T TOR/VE' Y H. N. JACKSON INTER-TUBE GAS BURNER FOR A COAL OR OIL-FIRED Feb. 23, 1965 WATERWALL. BOILER 4 She@ ts-Sheet 4 Filed April 29, 1963 I N VE N TOR. HERBERT NE/L JACKSON BY M ATTORNEY United States Patent O 3,170,443 INTER-TUBE GAS BURNER FOR A COAL R OIL-FIRED WATERWALL BOILER Herbert Neill Jackson, Don Mills, Toronto, Glntario, Canada, assigner to Eclipse Fuel Engineering Co., Rockford, Ill., a corporation of Iliinois Filed Apr. 29, 1963, Ser. No. 276,554 18 Claims. (Cl. 122-236) The present invention relates generally to burner constructions and has particular references to a novel nozzle mixing, multiple unit, burner construction which is designed for ring in between the closely spaced parallel water tubes of a waterwall-type boiler.

In many localities, the industrial use of fuel gas is limited either :by governmental regulation or by public utility policy. In :either event, household users of fuel gas are given preference over industrial users. Where governmental regulations in this matter prevail, fuel gas is not available for industrial use during certain periods, for example, between November l and March l5. Where the matt-er is left to public policy, the public utility company, being loathe to curtail service to households, will, during severe weather and when the supply of fuel gas is dangerously low, notify industrial users of fuel gas temporarily to discontinue their use of fuel gas.

In localities which are thus restricted, especially where large waterwall boiler installations are involved, manufacturers and other users of industrial heating equipment twho, if permitted to do so, would ordinarily use economical fuel gas for firing their boilers, find it unprotable to effect seasonal conversion of their boilers from fuel gas to coal or oil and vice versa, at least two such conversions being necessary each year. Instead, they prefer to burn either coal or fuel oil throughout the entire year,

dispensing with the use of fuel gas entirely. This isl readily understandable with the size of some installations is considered, together with the fact that the lire grate and other coal-burning adjuncts, as well as the Stoker equipment, for a 4given installation may weigh several tons and cost thousands .of dollars for effecting a conversion, to say nothing of the idle time consumed in making the conversion. Coal-burning equipment, once installed, usually is a permanent installation and Such equipment is not readily susceptible to repeated removal and replacement. Such equipment usually is designed for a given installation and is built yinto place to a large extent in an empirical manner and is intended to stay there permanently. To tear it down is to destory it at least in part.

Recently, considerable attention has been given to the possibility of designing fuel gas-burning equipment Which will lire a boiler without removing the coal-burning installation and can be used, when regulations are applicable, as a substitute firing means while allowing the regular coal-burning equipment to remain in place vwith ylittle or no dismantling thereof. One solution to the problem has arisen as a result of a newly-developed techniques in workmanship whereby the existing tubes of a waterwall boiler may be bent in their existing environment to an out-of-the-way position so as to create, in effect, a small window-like void or opening through the waterwall to allow a single burner nozzle to be projected through the opening for firing purposes. Specifically, adjacent vertical tubes :of a waterwall boiler are usually spaced apart a distance of approximately one and onehalf inches so that access to the interior of the combustion chamber through one of the waterwalls of the boiler by a conventional gas burner is impossible. According to the recently-developed technique referred to above, highly skilled workmen are able to push certain refractory combustionrblocks in the openings.

B'ZAB Patented Feb. 23, 1965 groups of tubes aside and away from a common center in opposite directions in order thus to create an opening in the waterwall large enough to accommodate a con-l ventional gas burner. Todo this, a selected section of the combustion chamber wall or casing is removed to expose the tubes from the outside of the boiler, and when the opening has been created, the burner assembly is bolt-ed in place so that the burner nozzle registers with the created opening. The risks involved, however, are great and there always is the danger of rupturi-ng a tube by unduly stretching it, or causing a tube to buckle by over-bending it. When this happens, costly repairs are necessary. Obviously, the boiler must be shut down for the length of time necessary to perform the operation.

The technique involved in performing such tube-bending operations is so dihicult that even the manufacturer of a given boiler ordinarily will not attempt to perform them and the workmen who are able to perform them must be imported for the purpose. This, of course, renders these operations costly, although once performed, the installation will serve its purpose throughout the remainder of the life of the boiler. It does, however, require seasonal alterations inasmuch as when the time arrives for use of the permanently installed coal-burning equipment, the fuel gas burner proper must be :removed and the combustion chamber wall section, which previously had been removed, replaced or an equivalent section bolted in place to close the wall opening. However, the waterwall opening that is established by the tubes which have been previously pushed aside is allowed to remain. With the fuel oil burner removed, the coalburning equipment may then 'be set into operation and it will function in the usual manner, although a small, amount of heat transfer effect may be lost due to the'; uneven tube distribution or tube bunching involved in the conversion.

While the procedure outlined above has enabled a waterwall boiler to be fired by fuel gas during such periods of time as the lgas is available, it does not represent an ideal solution to the problem of seasonal fuel gas curtailment. In the first place, the useof a single fuel gas burner of limi-ted size projecting through a small waterwall opening is not always sufficient to accommodate the capacity of the combustion chamber, and where a large waterfall boiler is concerned, it may be necessary to establish waterwall openings in more than one combustion chamber side wall. Functionally, fuel gas burners, Whether of the nozzle mixing type or of the premix type, when projected through relatively small waterwall openings, can develop very little radiant heat inasmuch as the size of the openings which can be created by pushing the waterwall tubes aside are not large enough to accommodate the ,positioning of Thus, due to the large volume of developed iue gas and a lack of radiant heat, such burners are not as eilicient as they are when they can be properly mounted in radiant combustion blocks.

The present invention is designed to overcome the abovenoted limitations that are attendant upon fuel gas conversion units for waterwall boilers, and toward this end, the invention contemplates the provision of a novel conversion unit which is in the form of an auxiliary burner for a coal or'oil-red waterwall boiler, is capable of permanent installation in one of the waterwalls of such a boiler, and after the initial installation thereof, may be permanently left in position. During periods when fuel gas is not available, the auxiliary burner unit or installation, although not in use, is not damaged by operation of the regular coal or oil-burning equipment, and during periods when fuel gas is available, its use has no effect upon the regular coal or oil-burning equipment. Stated otherwise, after the installation of the novel conversi'on unit, either it or the regular coal or oil burner equipment may selectively be set into operation, each to the exclusion ofthe other, the only conversion operations required being the turning of a few valves and the energization of the electrical control equipment such as the blower, the pilot and other auxiliary burner adjuncts.

The provision ofv aconversion unit of the character briefly outlined above and possessing the stated advantages being among the principal objects of the invention, more specically this object is attained by the provision of a burner assembly including a multiplicity of small nozzle mixing, jet producing, nozzle units, together with manifolding therefor by means of which they are supplied with fuel gas and air in correct proportions, and also by means of which they are maintained or positioned in a denite pattern or fixed arrangement which is conformableV with the original and undisturbed tube-spacing associated with theV particular portion of the waterwall to which the burner assembly as a whole is applied. The pattern is such that, with the assembly in place against the `portion of the waterwall selected for installation, the nozzle units extend in spaced parallel rows, the spacing lbetween adjacent rows being precisely equal to the spacing between adjacent waterwall tubes and the nozzle units all being projected between adjacent tubes and terminating just beyond the general plane of the tubes. Firing is thus accomplished between adjacent tubes and into the interior of Vthe combustion chamber. Whereas with a single burner inter-tube installation, firing through adjacent tubes which have been forcibly parted or separated in the manner previously described to establish a central opening for reception of the burner, a single localized flame jet is projected through the waterwall and into the interior of the combustion space or chamber, with the multi-nozzle burner assembly of the present invention a large number of small iiame jets are produced over a wide vexpanse of the waterwall. Further than this, at the time of the original installation and after the burner nozzles and their gas and air manifolding is in place, refractory material is packed around and about the waterwall tubes and the intertube-projected nozzles in such a manner as partially to embed the tubes and nozzles, while leaving small openings through the refractory material, each opening leading to a respective nozzle for conducting the llame jet therefrom and directing the same to the interior of the combustion chamber. Each of these small openings constitutes, in effect, a minute combustion block leading to the combustion chamber and the net effect of these multiple small combustion blocks is to establish a large area of radiant heat generation emanating from the refractory material and transmitting heat by radiation to the adjacent waterwall tubes, as well as to the interior of the combustion chamber, while at the same time heat is transmitted to these tubes by direct conduction from the contacting refractory material.V

During use of the regular coal or oil-burning equipment for boiler-firing purposes, the gas-burning equipment of the present invention remains in place but is not fired. Due to the fact that the various nozzle units and the .immediately adjacent portions of the gas and air mani- A:folding-is, for the most part, embedded in the Wall of refractory material which lines the installation, and in vwhich the adjacent Water Vtubes are similarly embedded,

these nozzles `and portions of the manifolding are thus shielded from the intense heat of the combustion chamber during coal or oil-firing of the boiler, while at the `same time, the adjacent water-containing tubes serve to conduct heat away from the nozzles and manifolding so that they will not reach burn-out temperatures.

The auxiliary burner assembly of the present invention is susceptible to wide variance in design and each installation that is made according to the invention is a custom jobinasmuch as in designing the installation, many considerations must be reckoned with. For

example, theV size or capacity of the waterwall boiler, the selection of the particular waterwall to which the installation is to be made, the disposition of water tubes which make up the Vselected waterwall, the distance be-V considerations that will aiect the nature of the air and gas-manifolding leading to the multiple burner Vnozzles and the manner in which such manifolding is supported in position adjacent to the selected Waterwall. The basic principles of the invention, however, remain undisturbed and the invention is applicable to a Wide variety of waterwall boilers simply by yprogressively and empirically building up manifolding to accommodate water tube distribution and effecting nozzle unit placement on the manifolding for proper inter-tube relationship and firing into the combustion chamber through or in between adjacent tubes over a Wide waterwall area, and finally applying refractory material to the multiple nozzle assembly, the latter step being a masonry job which is effected with the use of masonry tools, such as a trowel and appropriate sprue plugs and other masonry forms.

The provision of an auxiliary burner assembly which is safe from the standpoint of light-olf in that it will ignite to completionfrom nozzle row to nozzle row in chain Vreactioin fashionone'which, moreover, will thus light-off at low fire settings; one which has an extremely good turn-down factor; and one which, otherwise, is well-adapted to perform the services required of it, are

'further desirable features which have been borne in mind in the production and development of the present invention.

Numerous other objects and advantages ofthe invention not at this time numerated, will become readily apparent as the following description ensues.

In the accompanying four sheets of drawings forming a part of this specification, two illustrative embodiments of the invention have been shown.

In these drawings:

FIG. 1 is a fragmentary sectional view taken substantially vertically and transversely through the combustion chamber and surrounding waterwalls of an A- FIG. 3;

FIG. 5 is a sectional View taken on the line 5 5 of FIG. 3;

` FIG. 6 is a further enlarged fragmentary sectional view taken on the line 6-*6 of FIG. l;

FIG. 7 is a still further enlarged sectional view taken substantially centrally and longitudinally through a combinedY gas and air manifold leg employed in connection -with the present invention;

ployed in connection with the present inventionV and showing the same in its detached state; f

FIG.{9 is a top plan viewA of the burner tip shown in FIG. 8;

FIG. 10 is a fragmentary top plan View, partly in section, of the structure shown in FIG. 7;

FIG. 1l is a fragmentary sectional view taken substantially horizontally through the combustion chamber and surrounding waterwalls of another type of boiler and showing a modified form of auxiliary fuel gas burner assembly operatively installed in one side wall of the boiler;

FIG. 12 is an enlarged sectional View taken substantially along the line 12--12 of FIG. 1l; and

FIG.V 13 is a sectional View taken substantially along the line 13-13 of FIG. 12.

Referring now to the drawings in general, in FIGS.v

1 and 2 therev has -been fragmentarily illustrated a steamgenerating waterwall boiler of the type commonly referred to either as a type-A boiler or as an A-boiler by reason of the arched distribution of the water tubes or downcorners where they lead out from the steam drum at the top of the boiler and extend downwardly in divergent fashion toward the laterally spaced water drums therebeneath. In FIGS. 11, 12 and 13, there has been fragmentarily illustrated a steam generating waterwall boiler of the rectangular box type. For purposes of discussion herein, it may be assumed that each of the illustrated waterwall boilers is red by permanently installed coal-burning equipment which cannot conveniently be removed therefrom, the equipment being installed through one open end of the boiler casing and then closed by the boiler front wall. In each of the illustrated boiler assemblies, the combustion chamber is enclosed, in part, by vertical side and end waterwalls, the end wall being disposed at the end of the boiler opposite the permanently installed coal-burning equipment.

As heretofore stated, the present invention relates to an auxiliary burner construction or assembly which is made up of gas and air supply manifolding, together with a large multiplicity of small nozzle mixing, jet-producing nozzle units, the manifolding being designed to t a limited section of one o-f the waterwalls selected for the installation and in such a manner that portions of the mainfolding project in between adjacent vertical water tubes and carry the nozzle units in a uniformly distributed 4manner over a wide waterwall area and in appropriate positions where they may effectively re into the combustion chamber, the entire installation being made without necessitating bendingl or any disarrangement whatsoever of the original boiler tubing. In the boiler of FIGS. l and 2, a portion of the end waterwall has been selected for the auxiliary fuel gas burner assembly. In the boiler of FlGS. 1l, l2 and 13, a portion of one of the side waterwalls has ybeen selected for the assembly. Only one fuel gas burner installation has been shown in connection with each of the two illustrated forms of steam-generating boilers, 4but it will be understood that plural installations involving the same waterwall or involving different waterwalls of the same boiler assembly may be made if desired. Similarly, if desired, the installation may be made in the side waterwall of an'A-boiler or in an end waterwall of a rectangular box boiler. Ordinarily, each installation of an auxiliary fuel gas burner according to the present invention will be made on an empirical basis after selection of the'particular waterwall and the limited area thereof where the installation is to be made.

Referring now in detail to FIGS. 1 and 2, the A-boiler which is fragmentarily illustrated therein has been designated in its entirety by the reference numeral tu, and it involves in its general organization the usual upper longitudinally extending steam drum 12, lower laterally spaced parallel water drums 14 and le, and interconnecting water tubes which have individually been designated by the reference numeral 1S. The various tubes 18 are arranged in banks, one bank constituting one side waterwall 2th, another bank constituting the other side Water- Wall 22, and a third bank constituting the end waterwall 24. It is to be understood that the end waterwall 24 is disposed longitudinally opposite to the end of the boiler combustion chamber within which there is permanently installed suitable and conventional coal or oilburning boiler-firing equipment (not shown). 1n the case of coal-burning equipment, the grate, Stoker nights and other instrumentalities may extend well into the combustion chamber which is, in part, defined by the three waterwalls 2d, 22 and 2d.

The steam drum l2, the ywater drums 14 and 15, and the water tubes 1S are suitably enclosed in an outer boiler casing including refractory-lined side walls 26 and 28, and a rear end wall structure 39, these being `the only walls illustrated herein. Other specific structural boiler details, such as the character of the refractory casing walls, the presence of baiiie plates, tube supports, interconnecting wal xtures or plates, supporting beams and columns and the like, appear in the drawings but have not been specifically described herein since they bear little relation, if any, to the structure or function of the present invention. Similarly, other details such as intertube connections, coal or oil-ring equipment such as the grate and the Stoker mechanism for feeding coal to the latter, and other functional instrumentalities which are ordinarily associated with A-boi-lers of the type illustrated herein, have been omitted in the interests of clarity. It is deemed sucient in order to relate the disclosure of FlGS. l and 2 to the present invention, to state that the two water drums ld and fears suitably supported from the combustion chamber lioor on pedestals 32 and that the tubes 13 which make up the side waterwalls Zti and 22 extend vertically from the water drums 14 and le for an appreciable distance and then are bent as at 34 so that they form an arch over the combustion chamber and lead into the steam drum 12 as clearly shown in FIG. l. The tubesl of the rear end waterwa-ll 24 extend inwardly on an incline and toward each other as they leave the water drums ld and 16, and then they are bent as at 36 so as to extend vertically to produce the vertical portion of the end waterwall 24, after which they are again bent as at 33, lwhere required, so that they may converge into the steam drum 12.

The arrangement of parts thus far described is purely conventional and no claim is made herein to any novelty associated with it, the noveltyof the present invention residing rather in the manner and the means by which one of the three waterwalls, namely, the end waterwall 24 is modifie-d to accommodate positioning therein of an auxiliary burner assembly including small nozzle mixing burner units lwhich are caused to fire between the tubes 13 of the end waterwall 2d, and manifolding for furnishing `fuel gas and air to such nozzle units, all in a manner that will be made clear presently.

Still referring to FIGS. 1 and 2, a burner assembly which has been tailored, so to speak, to fit -a selected area `or region of the waterwall 2d has been-designated in its entirety by the reference numeral 5t), and as shown in FlG. 2, it comprises a composite windbox 52 within which there is operatively installed gas manifolding 54 (see also FIGS. 4, 5 and 6). Portions 55 of the windbox project through the inter-tube spaces existing between adjacent water tubes 18 which cooperate to make up the waterwall 2d, and Vin combination with the adjacent portions of the gas manifolding, establish a series of small nozzle-mixing burner nozzle units 6@ (see FIG. 7). These nozzle units 60 are distributed in spacedV rows over a fairly expansive area of the end waterwall 24, the area assuming the generally triangular shape of the portion of the waterwall 24 which immediately underlies the tube arch above the tube bends 34 in the tubes 18. To accommodate positioning of the windbox 52 closely adjacent to the outside area'of the end waterwall 24, a portion of the original boiler casing end wall structure 39 is cut away to create an opening 62 for the windbox. The windbox is then set into the opening 62 and the projecting portions V56 thereofV at the front ofthe windb project between adjacent tubes to position the nozzle units Y60 Vin their proper inter-tube relationship. As will be ox are caused to set forthY in greater detail presently, after the windbox and its contained gas manifolding 54 are in position within the opening 62, masonry operations are performed to establish a tube and nozzle-embedding refractory wall 64, this wall leaving only limited areas 66 (see FIG. 6) of the tubes 18 exposed to the interior of the combustion chamber, and establishing small passageways 66 leading to the burner nozzle units 66. As will be described in greater detail when the operation of the present burner assembly is set forth, these small passageways 68 constitute,. in effect, individual combustion blocks for enhancing the efficiency of the burner nozzle units by assimilating and radiating heat, as well as by confining the products of combustion in these localized areasy long enough to attain stoichiometric conditions. f

Referring now Vto FIGS. 2, 6 and 7 wherein the structural details of the Windbox 52 are best illustrated, the Windbox consists of two main sections including an inside section 70 and an outside section '72, the two sections being provided with flanges 74 and suitably connected together at the flanges. The flanges 74 tit against the outside face of the rear end wall 30 of the outer boiler casing and thus constitute attachment means for the windbox as a whole. The box-like structure which comprises the Windbox 52 includes end walls 76 and '78. A lead-in gas pipe S6 enters the windbox through the end wall 76 and is connected to the gas manifolding 54 for fuel gas supply purposes. The Windbox 52 also includes a vertical outside wall 82 and a vertical inside wall 84. Horizontal top and bottom walls 86 and 88 serve to complete the closed windbox structure. An air supply conduit 90, which may be connected to a suitable motor-driven blower (not shown), communicates with the interior of the windbox 52 through an opening 91 in the bottom wall 88.

The inside vertical wall 84 of the windbox is in the form of a plate having formed therein a series of vertical elongated spaced parallel slots 92 (see FIGS. 2, 6 and 7). These-slots are spaced apart a distance commensurate with the spacing of the water tubes 18 in the waterwall 24 and are positioned in register with the inter-tube spaces of the waterwall. The previously mentioned projecting portions 56 of the Windbox 52 are in the form of separate U-shaped or trough-like plates having lateral attachment flanges 94 by means of which they are secured to the vertical inside wall S4 of the windbox 52 in position over the vertical slots 92. The U-shaped projecting portions S6 are coextensive with the slots 92 which they cover so that they provide, in effect, a series of bays on the inside wall 84, the bays projecting in between adjacent vertical portions of the water tubes 18 of the waterwall 24. The U-,shaped plates which constitute the projecting portions 56 of the Windbox 52 are secured in position on the vertical inside wall 84 by bolt and nut assemblies 95. At the base of each projecting portion 56, a perforated plate or screen 96 extends across the associated opening and is secured in position by a retaining plate 96, the plate being held in position by means of the bolt and nut assemblies 95. In order to hold the projecting portions 56, the screens 96 and the retaining plates 98 securely in their assembled relationship on the inside wall 84, the use of welds is resorted to, there being welds between the nut and bolt assemblies95 and the anges 94, and welds 102 between the screens 96 and the inner side wall 84.

Each of the U-shaped projecting portions 56 of the windbox 52 has formed therein a plurality of circular openings 104 (see FIGS. 7 and 10), these openings being designed to receive therein respective burner nozzle rings 106 in associated relation with the various nozzle units 61B. The nozzle rings 166 closely t the circular openings 194 and are welded in position Within the openings as shown at 108. The openings andk their associated nozzle rings are arranged in three parallelrows longitudinally along rings may best be seen in FIGS. 7 and 10.

the curved bightregion of the'projecting portions 56, one row being centered on the bight region and the other two rows being disposed on opposite sides of the center row.. The circular openings 104 in adjacent rows are staggered and the various rows are substantially coextensive with the vertical extent of the projecting portions 56. This disposition of the openings and their associated 4nozzle Still referring to FIGS. 7 and `10, each nozzle ring 166 constitutes a functional element of one ofthe individual nozzle units 6% and each unit further includes a short leadout nipple 11i), the inner end of which is threadedly received as at 112 in a local manifold pipe 114, and the outer end of which is threadedly Vreceived as at 116 in Va burner nozzle tip 118. The local manifold pipes 114 constitute elements of the previously-mentioned gas manifolding S4. f

One of the nozzle tips 11S is illustrated in FIGS. 8 and 9, and it consists of a generally cylindrical cup-shaped body having a threaded socket 121B formed therein for threaded reception over the -outer end of the associtaed lead-out nipple 111B. The illustrated tip is provided with a cylindrical side face 122 and a frusto-conical outer surface 123 which surrounds the cylindrical end face 124 of the tip. A screw driver receiving kerf or slot 126 by means of` which the tip may be applied to the associated leadout nipple 111i extends diametrically vacross the circular end face 124. Inclined gas Vpassages 123 extend in divergent fashion through the tip and establish communication between the threaded socket and the exterior of the tip, the passages 128 opening onto the frustoconical surface 123. When threaded onto the outer end of the associated lead-out nipple 110, the tip 11S is maintained centered within the adjacent nozzle ring 1% as shown in FIG. 7.

The gas manifolding 54, in addition to the various local manifold pipes 114, further includes a horizontally extending main gas manifold 130 (see FlG. 3) from which there extends at spaced regions therealong a lseries of branch manifold arms 132. Each branch manifold arm includes a vertical leg 134 and a horizontal Vleg 136 (see FIG. 4), the vertical leg communicatingdirectly with the manifold 130 and the horizontal leg communicating directly With one of the local manifold pipes 114i. The main gas manifold 13d and, consequently, Vthe manifolding 54 in its entirety, is rigidly Vsecured within the windbox 52 by means of a Series of U-bolts and clamping straps 142. The latter are supported from brackets 14d which are suitably secured to the inside wall Sd of the windbox 52. The gas manifolding 54 is so designed and secured in position within the windbox 52 that the various local manifold pipes 114i are centered within the respective projecting portions 56 and so that each nozzle Vring 196 will receive therein one of the nozzle tips 113 in operative relationship.

It is to be noted that the gas manifolding 54 of PIG` 3 is capable of progressive unit assembly so that the'manifolding may be tailored to lit diiferently shaped windboxes which may be used in connection Vwith different waterwall boilers. The main gas manifold 131? is in the form of a casting of elongated tubular cylindrical design, and has oppositely-directed radial, internally-threaded leg connections 159 disposed at equallyV spaced'regions therealong. The spacing of the leg connections 151B may be predicated upon the diameter and spacing of the water tubes in the waterwall of a given installation, these dimensions being fairly well standardized in the boiler industry. The branch manifold arms 132 comprise different length pipe sections 152 and elbows 154 so that by proper selection of pipe sections, the radial span of any given manifold arm may be attained. Such leg connections as are not used may be closed by plugs 156. In the installation herein illustrated by way of example, the area of the Waterwall 24 to be tired in an inter-tube manner is, as previously stated, a generally triangular area. For an expeditious supply of fuel gas to the local manifold pipes 114 which extend between adjacent water tubes 1S of the waterwall 24 and terminate in the same general horizontal plane near the bottom or base of the triangle as shown in FIG. 3, the main gas manifold 13@ is disposed at an elevated level above the triangle base and the central group of local manifold pipes 114 are served by dual manifold arms 132 of wide vertical span, whereas the local manifold pipes 114 in the lateral end regions of thetriangle are served by single manifold arms 132 of varying length. The lead-in gas pipe 8i! is connected by a coupling 15'? (see FIG. 2) outside of the windbox to a gas supply pipe 158 which leads from a suitable source of fuel gas under pressure. l

After the windbox 52 and its contained manifolding 54 have been installed upon the selected area of the waterwall 24 in the manner previously described, the refractory Wall 64 is installed from the inside of the combustion space, the services of a mason utilizing conventional masonry tools being required. The wall 64 is built-up on the inner faces of the tubes 1S and on the curved bight portion along the distal edges of the various projecting portions 56 of the windbox 52 where these portions project between adjacent Water tubes 18. When the refractory wall 64 Vis completed, it takes on the appearance of a corrugated structure having vertically elongated humps or ribs 161B (see FIGS. 2 and 6) which are centered over the projecting portions 56, and troughs 162 which leave the areas 6e of the water tubes 18 exposed to the combustion space within the boiler casing. The previously-mentioned passageways 68 extend through the ribs 166, lead to the various nozzle rings 166 (see FIGS. 6 and 7) and, in effect, establish small combustion blocks for gas and air mixture emanating from such nozzle rings, thereby enhancing the combustion of gases at or near the nozzle units di), as Well as enhancing the radiant heat characteristics of the refractory wall 64 as a whole.

In the operation of the A-boiler lil, during the period when gas is not available for use, the regular boiler firing equipment (either coal or oil) is utilized in the usual manner of operation of such equipment and without in any Way disturbing or modifying the inter-tube firing auxiliary gas burner assembly of the present invention. During such use of the boiler 1t), the ow of relatively cold water from the water drums 14 and 16 through the vertical Water tubes 18 gives the effect of a water jacket to the projecting portions 56 Iof the windbox 52, and, consequently, to the 'Various nozzle units 62 which to a large extent are embedded in the refractory Wall 64. The nozzle units are, therefore, at all times maintained below burn-out temperatures and are not damaged by coal or oil-firing of the boiler.

During such periods as fuel gas is available for use, the coal or oil-burning equipment is left intact and in position within the combustion space of the boiler and none of the adjuncts associated therewith, such as the Stoker mechanism, the blower, and the like, need be disturbed. In order to ignite the burner assembly of the present invention and as shown in FIGS. 1 and 2, a pilot tube 170 projects outwardly through a suitable hole 172 in the refractory Wall 64 near the base of the triangular wall structure and preferably in the central regions of the base. The flame from this pilot tube is adequate for ignition purposes since the close proximity of the various nozzle units 60 and their associated combustion block passageways 68 to one another assures chain reaction ignition of the entire combustion area of the burner assembly. In this regard, it is to be noted that because of the corrugated or ribbed character of the inside lface of the refractory Wall 64 and the fact that certain of the vertical rows of passageways 6g in adjacent ribs or corrugations generally oppose each other, this chain reaction ignition is greatly enhanced so that ignition Will take place over the entire combustion area, even under low fire conditions. The burner assembly will reach full firing in a minimum of l@ time at low turn down settings and thus any .danger of explosion is obviated. In FIGS. 11, 12 and 13, an installation of the auxiliary burner assembly of the present invention is shown as being applied to a waterwall boiler 210 of the rectangular box type. In this arrangement, the installation is made kthrough one side waterwall of the boiler instead of Vthrough the end wall that is remote from the regular coal or oil tiring equipment.

In many respects, the installation of FIGS. ll, 12 and 13 is similar to the installation of FIGS. l and 2 and, therefore, in order to avoid needless repetition of description, similar characters of reference but of a higher order have been applied to the corresponding parts as between the disclosures of the two groups of figures in the drawings.

FIG. l1 of the drawings is a horizontal sectional view taken through the boiler 210 at a level appreciably above the level of the boiler combustion space oor and at a region where the combustion space is surrounded by four waterwalls including side waterwalls 220 and 222, a rear end waterwall 224, and a front end waterwall 225. It will be understood that the coal or oil-burning equipment (not shown herein) will be installed through a lower opening in the front end waterwall 225 where the water tubes 218 are discontinued for clearance purposes. The casing side wall selected for the installation of the fuel gas auxiliary burner assembly of the present invention is the side Wall 226. The installation is made through the upper regions of this side wall 226 and, consequently, in the upper regions of the side waterwall 220. Since in the installation of FiG. ll there are no arched Water tubes 18 at the top of the boiler, the expansive area of the various nozzle units 260 which are associated with, and form parts of, the burnery assembly may be made generally retangular. The generally rectangular windbox 252 is installed in the rectangular opening 262 in the casing side Wall 226 as in the previously described form of the invention and the inside wall 2&4 of the windbox 252 is of rectangular design to accommodate the rectangular combustion area of the various nozzle units 260. This necessitates a different arrangement of the gas manifolding 254 within the windbox, and, accordingly, the lead-in gas pipe 280 has two radial leg connections 350 extending to twin manifolds 330. These latter manifolds 331i are connected by manifold pipes 332 of equal extent to the various local manifold pipes 314, as shown in FIG. 13. Otherwise, the details of the burner assembly which is associated with the box-type boiler 21d are substantially identical with the details of the burner assembly which is associated with the A-boiler of FIGS. 1 and 2 so that further and detailed description is unnecessary.

The operation of the burner assembly of FIGS. 1l, l2 and 13 is substantially the same as the operation of the burner assembly of FIGS. l and 2 except for the fact that the various nozzle units 260 fire transversely across the combustion space instead of longitudinally therealong. Both of the herein described installations are of a permanent nature, the installations remaining in place but being inactive during periods when the regular coal or oil-burning equipment is in use. riods when fuel gas is available for use, these installations are set into operation in the manner previously described While the regular iring equipment remains in position but inactive.

The invention is not to be limited to the exact arrangement of parts shown in the accompanying drawings or described in this specification as various changes in the details of construction may be resorted to without departing from the spirit or scope of the invention. For example, While in the illustrated forms of waterwall boilers, only one fuel gas burner installation has been made in either the end wall or a selected side wall of the boiler casing, it may be found practicable in certain instances to effect plural fuel gas installations in connection with Conversely, during pethe same waterwall'of the boiler.

of a dual nature with one installation made in each side wall, in one side wall and` one end wall, or the installations may be made in both side walls and one end wall. Under certain conditions, where there may be interfering equip,- ment along a particularly large waterwall that would prevent the creation of a large burner expanse installation, plural small expanse installations may be made in Therefore, only insofar as the invention has been particularly pointed out in the accompanying claims is the same to be limited.

Having thus described the invention, what I claim as new and desire to secure by Letters Patent is:

1. The combination with a water tube boiler having means forming an internal combustion chamber and including a vertical waterwall comprised of closely spaced parallel water tubes which lie in a common Vertical plane,

'and also having an outside boiler casing extending around the chamber-forming means and including a vertical wall structure adjacent to, and substantially coextensive with, said waterwall, of an auxiliary fuel gas burner assembly for 'firing said combustion chamber, said burner assembly ycomprising a windbox operatively installed in said wall structure and having an inside Wall disposed in close proximity to a selected area of the outside face of said waterwall, said inside wall being provided with a plurality of hollow projecting portions providing bays which enter between adjacent water tubes of the waterwall and extend into the combustion chamber, said projecting portions being of velongated trough-like design, each projecting portion being substantially coextensive with a span of the selected area, the distal edge region of each projecting portion being formed with a series of spaced openings therealong, a

gas manifold disposed within said windbox and having lead-out nipples extending to and in register with said ',openings, and in combination therewith, defining a series of small nozzle-mixing gas-burning nozzles, means for supplying air under pressure to the windbox, and means for supplying fuel gas under pressure to said gas manifold.

2. The combination set forthr in claim 1 and wherein said projecting portions of the inside wall of the windbox terminate in close proximity to the inside face of said waterwall. Y Y

3. The combination with a water tube boiler having means forming an internal combustion chamber and including a vertical waterwall comprised of closely spaced parallel water tubes which lie in a common vertical plane, and also having an outside boiler casing extending around the chamber-forming means and including a vertical wall structure adjacent to, and substantially coextensive with, said waterwall, of an auxiliary fuel gas burner assembly for firing said combustion chamber, said burner assembly comprising a windbox operatively installed in said wall structure and having an inside wall Vdisposed in close proximity to a selected area of the outside face of said waterwall, said inside wall being provided with a plurality of enlongated hollow projecting portions of trough-like design and which provide bays that enter between adjacent water rtubes of the waterwall and extend into the combustion chamber, each projecting portion being substanltially coextensive with a linear span of the selected area, the distal edge region of each projecting portion being of convex generally semi-cylindrical design and being provided with two spaced parallel rows of equally spaced openings therealong, kone on each side of the apex line of the projecting portion soy that the openings open into the combustion chamber along divergent planes, a gas manilfold disposed within saidvwindbox and having lead-out `nipples extending to and in register with said openings,

and in combination therewith, defining two series of inclined small nozzle-mixing fuel vgas-burning nozzles, means vfor supplying air under pressure to the windbox, and

means .for supplying gas under pressure to said gas manifold. Y

4. The combination set forth in claim 3 and including,

Vvertical waterwall comprised of closelyy spaced parallel water tubes which lie in a common vertical plane, and also having an outside boiler casing extending around the chamber-forming means and including a vertical wall structure adjacent to, and substantially coextensive with, said waterwall, of an auxiliary fuel gas burner assembly for firing said Vcombustion chamber, said burner assembly comprising a windbox operatively installed in said wall structure and having a dat inside wall disposed in close proximity 'to a selected area of the outside face of said waterwall, said inside wall being provided with a plurality of vertically elongated hollow projecting portions of trough-like design and which project forwardly out of the plane of the flat inside wall and provide bays that enter between adjacent vertical water tubes of the waterwall and extend into the combustion chamber, said projecting portions being substantially coextensive with respective linear spans of the selected area, the distal edge region of each 'projecting portion being of curved semi-cylindrical design and being provided with a central vertical row of equally spaced openings therealong lying on the apex line of the projecting portion, and'with two vertical rows of equally spaced openings spaced from the apex line andon opposite sides thereof respectively, a gas manifold disposed within said windbox and having lead-out nipples extending to vand'in register with said openings, and in combination therewith, defining three series of small nozzle-mixing fuel gas-burning nozzles, means for supplying air under pressure to the windbox, and means for supplying gas ,under pressure to said gas manifold.

,.-7.YThe combination set forth in claim 6 and wherein lthe apice's'of the projecting portions-terminate in close proximity to the inside face of said waterwall.

8. The combination` set forth in claim 6 and including, additionally, a perforated air distribution plate extending across the base region of each of said projecting portions within the windbox.

9. The combination set forth in claim'6 and wherein the spaced openings of adjacent rows in each projecting portion are staggered. l v

10. The combination set forth in claim 6 and wherein the spacing between adjacent openings'of each row and the disposition of* such openings in the rows are such that the openings of adjacent projecting portions oppose one another in pairs to enhance the light-off and turndown characteristics of the burner-assembly.

l1.V The combination with a waterwall boiler having means forming an internal lcombustion chamber and including a vertical waterwall comprised of closely spaced parallel water tubes which lie lin a common'plane, and also having an outside boiler casing extending around the chamber-forming means and including a vertical wall structure adjacent to, and substantially coextensive with, said waterwall, of an auxiliary fuel gas burner assembly for firing said combustion chamber, said burner assembly comprising a vwindbox operatively installed in the wall structure and havingV a flat inside wall disposed in close proximity to a selected area Vof the outside'face of said waterwall, said inside wall being provided with a plurality of vertically-elongated hollow projecting portions of trough-like design and which project forwardly out of the plane of the inside wall and provide bays that enter between adjacent vertical water tubes and extend into the combustion chamber and terminate adjacent to the in- 13 side face of the waterwall, the distal regions of said projecting portions -being Vformed with openings therein which extend in vertical rows, a molded refractory wall intimately bonded to the inside face of the waterwall within the combustion chamber in heat exchange relationship with the water tubes thereof and with the distal regions of the projecting portions, said refractory wall being formed with passageways for the products of combustion and which are in register with the openings and establish communication between the openings and the combustion chamber, a gas manifold disposed within said windbox and having lead-out nipples extending to and in register with the openings, and in combination with the openings, defining a series of small inter-tube nozzlemixing gas burning nozzles, means for supplying gas under pressure to said manifold, and means for supplying air under pressure to the windbox.

12. The combination with a waterwall boiler having means forming an internal combustion chamber and including a vertical waterwall comprised of closely spaced parallel water tubes which lie in a common vertical plane, and also having an outside boiler casing extending around the chamber-forming means and including a vertical wall structure adjacent to, and substantially coextensive with said waterwall, of an auxiliary fuel gas burner assembly for firing said combustion chamber, said burner assembly comprising a windbox operatively installed in the wall structure and having a flat inside wall disposed in close proximity to a selected area of the outside face of said waterwall, said inside wall being provided with a plurality of vertically elongated hollow projecting portions of trough-like design and which project forwardly out of the plane of the inside wall and provide bays that enter between adjacent vertical water tubes and extend into the combustion chamber and terminate in close proximity to the inside face of the waterwall, the distal regio-n of each of said projecting portions being of semi-cylindrical design and being provided with two spaced parallel rows of equally spaced openings therein lying on opposite sides of the apex line of the semi-cylindrical distal region, said openings establishing communication between the interior of the windbox and the combustion chamber, a molded refractory wall intimately bonded to the inside face of the waterwall within the combustion chamber in heat exchange relationship with the water tubes thereof and with the distal regions of the projecting portions, said refractory wall being formed with passageways for the products of combustion and which are in register with the openings and establish communication between the openings and the combustion chamber, a gas manifold disposed within said windbox and having lead-out nipples extending to and in register with the openings, and in combination with the openings, defining a series of small intertube nozzle-mixing gas-burning nozzles, means for supplying gas under pressure to said manifold, and means for supplying air under pressure to the windbox.

13. The combination set forth in claim 12 and wherein the spacing between adjacent openings in each row and the disposition of such openings in the rows are such that the openings of adjacent projecting portions oppose one another in pairs to enhance the light-off and turndown characteristics of the burner assembly.

14. The combination with a water tube boiler having means forming an internal combustion chamber and including a vertical waterwall comprised of closely spaced parallel water tubes which lie in a common vertical plane, and also having an outside boiler casing extending around the chamber-forming means and including a vertical wall structure adjacent to, and substantially coextensive with, said waterwall, of an auxiliary fuel gas burner assembly for tiring said combustion chamber, said burner assembly comprising a windbox operatively installed in the wall structure and having a flat inside wall disposed in close proximity to a selected area of the outside face of said waterwall, said inside wall being provided with a plurality of vertically elongated hollow projecting portions of trough-like design and which project forwardly out of the plane of the inside wall and provide bays that enter between adjacent vertical water tubes and extend into the combustion chamber and terminate in close proximity to the inside face of the waterwall, the distal edge region of each of said projecting portions being of semi-cylindrical design and being provided with a central vertical row of equally spaced openings therealong lying on the apex line of the projecting portion, and with two vertical rows of equally spaced openings spaced from the apex line and on opposite sides thereof respectively so that the openings of said two vertical rows open into the combustion chamber along divergent planes, a molded refractory wall intimately bonded to the inside face of the waterwall within the combustion chamber in heat exchange relationship with the water tubes thereof and' with the distal semi-cylindrical edge regions of the projecting portions, said refractory wall presenting an inwardly facing ribbed surface to the combustion chamber with one rib overlying each water tube in the selected area, the ribs of said refractory wall being formed with passageways therein in register with the openings in the projecting portions and establishing communication between the openings and the combustion chamber, a gas manifold disposed within the windbox and having lead-out nipples extending to and in register with the openings, and in combination with the openings, defining a series of small inter-tube nozzles adapted to lire into said passageways, means for supplying gas under pressure to said manifold, and means for supplying air under pressure to said windbox.

15. The combination set forth in claim 14 and wherein limited surface portions of each water tube are exposed directly to the interior of the combustion chamber at the bottoms of the trough portions which exist between adjacent ribs of the refractory wall.

16. The combination set forth in claim 14 and wherein the passageways through the ribs are flared outwardly away from the respective openings with which they are in register and wherein limited surface portions of each water tube are exposed directly to the interior of the combustion chamber at the bottoms of the trough portions which exist between the adjacent ribs of the refractory wall.

17. The combination with a waterwall boiler having means for forming a combustion chamber and including a vertical waterwall comprised of closely spaced, vertically disposed, parallel water tubes which lie in a common vertical plane, of an auxiliary fuel gas burner assembly for firing said combustion chamber, said burner assembly comprising a series of vertically spaced small flame jetproducing gas burner nozzles projecting into and through the space existing between each pair of adjacent water tubes of said waterwall and terminating in close proximity to the inside face of the waterwall, and manifold means for supplying gas and combustion air to said nozzles.

18. The combination with a waterwall boiler having means forming an internal combustion chamber and including a vertical waterwall comprised of closely spaced vertically disposed parallel water tubes which lie in a common vertical plane, of an auxiliary fuel gas burner assembly for firing said combustion chamber, said burner assembly comprising a series of vertically spaced small ame jet-producing gas burner nozzles projecting into and through the space existing between each pair of adjacent water tubes of said waterwall and terminating in close proximity to the inside face of the waterwall, a molded refractory wall intimately bonded to the inside face of the waterwall within the combustion chamber in heat exchange relationship with the water tubes thereof overlying said burner nozzles, said refractory wall being formed with a series of passageways for the products of combustion emanating from said nozzles and which are in Vregister with the nozzles and establish communication 2,392,822 1/46 Kuhner 122-235 5 PERCY L. PATRICK, Primary Examiner.

v`KENNETH, W. SPRAGUE, ROBERT A.

8/49 Fletcher 122-235 3/56 Reed 6/ 60 Patterson V- OLEARY, Examiners. v 

1. THE COMBINATION WITH A WATER TUBE BOILER HAVING MEANS FORMING AN INTERNAL COMBUSTION CHAMBER AND INCLUDING A VERTICAL WATERWALL COMPRISED OF CLOSELY SPACED PARALLEL WATER TUBES WHICH LIE IN A COMMON VERTICAL PLANE, AND ALSO HAVING AN OUTSIDE BOILER CASING EXTENDING AROUND THE CHAMBER-FORMING MEANS AND INCLUDING A VERTICAL WALL STRUCTURE ADJACENT TO, AND SUBSTANTIALLY COEXTENSIVE WITH, SAID WATERWALL, OF AN AUXILIARY FUEL GAS BURNER ASSEMBLY FOR FIRING SAID COMBUSTION CHAMBER, SAID BURNER ASSEMBLY COMPRISING A WINDBOX OPERATIVELY INSTALLED IN SAID WALL STRUCTURE AND HAVING AN INSIDE WALL DISPOSED IN CLOSE PROXIMITY TO A SELECTED AREA OF THE OUTSIDE FACE OF SAID WATERWALL, SAID INSIDE WALL BEING PROVIDED WITH A PLURALITY OF HOLLOW PROJECTING PORTIONS PROVIDING BAYS WHICH ENTER BETWEEN ADJACENT WATER TUBES OF THE WATERWALL AND EXTEND INTO THE COMBUSTION CHAMBER, SAID PROJECTING PORTIONS BEING OF ELONGATED TROUGH-LIKE DESIGN, EACH PROJECTING PORTION BEING SUBSTANTIALLY COEXTENSIVE WITH A SPAN OF THE SELECTED AREA, THE DISTAL EDGE REGION OF EACH PROJECTING PORTION BEING FORMED WITH A SERIES OF SPACED OPENINGS THEREALONG, A GAS MANIFOLD DISPOSED WITHIN SAID WINDBOX AND HAVING LEAD-OUT NIPPLES EXTENDING TO AND IN REGISTER WITH SAID OPENINGS, AND IN COMBINATION THEREWITH, DEFINING A SERIES OF SMALL NOZZLE-MIXING GAS-BURNING NOZZLES, MEANS FOR SUPPLYING AIR UNDER PRESSURE TO THE WINDBOX, AND MEANS FOR SUPPLYING FUEL GAS UNDER PRESSURE TO SAID GAS MANIFOLD. 